1. Technical Field
The present invention relates to a method and system for recovering computer systems in general, and in particular to a method and system for recovering a computer system having a damaged local loadsource.
2. Description of the Prior Art
In order to ensure data recovery from site disasters such as fire, flood, earthquake, or even bomb at a computer site, all data on direct access storage devices (DASDs) of a main computer are usually duplicated at a remote location. Many computer systems such as AS/400(trademark) manufactured by International Business Machines Corporation, support data duplication in the form of mirroring local DASDs to DASDs located at a remote location. By so doing, at least one extra set of data is available for quick recovery should a disaster occur at the main computer site.
One of the DASDs located at the main computer site, typically known as a local loadsource DASD, contains system code utilized to perform initial program load (IPL) of the computer system. Hence, the entire local loadsource DASD, containing both system configuration data and application data, must be mirrored on the DASD located at the remote site in order to provide a quick data recovery should the local loadsource DASD become damaged or is damaged for any reason. Be that as it may, most computer systems do not support remote IPL (i.e., IPL from a mirrored loadsource DASD at the remote site) because of cost and complexity.
For computer systems that do not support remote IPL, the following problems may occur. After the occurrence of a disaster at the main computer site, a replacement computer system must typically be utilized to make connection with the loadsource DASD at the remote site. However, the replacement computer system cannot perform an IPL from the loadsource DASD at the remote site. This is because in order to establish a communication between the replacement computer system and the loadsource DASD at the remote site, the replacement computer system must first be loaded with communication software, and the problem is that the preliminary IPL process has not proceeded far enough to load the communication software onto the replacement computer system. There are two current solutions to this problem. The first solution is to transfer the loadsource DASD from the remote site and then attach it to the replacement computer system at the main computer site. But in order for this type of local attachment to be possible, the loadsource DASD from the remote site must be restricted to a type and format that can be attached to the replacement computer system. Furthermore, the loadsource DASD from the remote site must be physically transported to the local site.
The second solution is to provide the replacement computer system with some special hardware and Read-Only Storage code that can establish communications with the loadsource DASD at the remote site. Then, when the local loadsource DASD is damaged, the replacement computer system can perform an IPL directly from the loadsource DASD at the remote site.
The two solutions mentioned above are not optimal because the first solution is rather time consuming and the second solution is quite expensive. Consequently, it would be desirable to provide an improved method and system for recovering a computer system having a damaged local loadsource DASD by utilizing a loadsource DASD located at a remote location.
In view of the foregoing, it is therefore an object of the present invention to provide an improved method and system for recovering computer systems.
It is another object of the invention to provide an improved method and system for recovering a computer system having a damaged local loadsource.
It is yet another object of the invention to provide an improved method and system for recovering a computer system having a damaged local loadsource by utilizing a loadsource located at a remote location.
In accordance with the method and system of the present invention, after a catastrophic disaster and the installation of a replacement local loadsource direct access storage device, an indicator within the replacement local loadsource direct access storage device is set, such that the local loadsource direct access storage device cannot be utilized for initial program load. Thereafter, the contents of the entire loadsource direct access storage device located at a remote location are copied to the replacement local loadsource direct access storage device. The indicator within the replacement local loadsource direct access storage device is reset such that the local loadsource direct access storage device can be utilized for initial program load again. Finally, an initial program load is performed from the replacement local loadsource direct access storage device.
All objects, features, and advantages of the present invention will become apparent in the following detailed written description.